docs: def extract_source_geom(dstore, srcidxs):
      """
      Extract the geometry of a given sources
      Example:
      http://127.0.0.1:8800/v1/calc/30/extract/source_geom/1,2,3
      """
      for i in srcidxs.split(','):
          rec = dstore['source_info'][int(i)]
          geom = dstore['source_geom'][rec['gidx1']:rec['gidx2']]
          yield rec['source_id'], geom